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| Ventilation, Allergies, House Dust Mites & Asthma |
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 Is inadequate house ventilation giving us asthma and encouraging allergies?
Compared to our recent ancestors, as 21st century human beings we spend a considerable part of our lives indoors whilst at home and, for most of us, indoors whilst we work. Some suggest that as humans we now spend as much as 80% of our time indoors. The air we breathe whilst at work is subject to many controls and regulations, yet prior to the new 2006 Building Regulations, relatively few such regulations existed for our own homes. Maintaining the quality of the air in our homes is almost certainly as important as the quality of the air we breathe at work. In fact, it is probably of more importance for some family members such as children, pregnant women, the elderly, and anybody suffering from respiratory diseases such as asthma.
Inadequate ventilation is a big issue in newer houses, flats and some older houses that have been sealed with replacement doors and windows. In many older homes (say early 1960's and before) the level of indoor air pollution is quite low because the original construction of buildings was not subject to tight insulation and air-tightness regulations. Fresh air infiltrates through poorly fitted doors and windows as well as the chimneys, and pollutants can leak out via the same. Admittedly, some of the more poorly designed houses have their own problems, such as damp due to the lack of a DPC, but the majority were much more ventilated than they are now. Although much of our older housing stock has already been 'improved' to minimise heat loss by the addition of double glazing, cavity wall and roof insulation, the addition of tightly fittings doors etc., it is likely that it still naturally ventilates more than new build properties.
Later and new build housing has been, and is, subject to much more stringent insulation and air-tightness regulation. However, despite there also being regulations around how much air change should be designed into them, relatively few have integral chimneys and many have now turned into almost hermetically sealed units. Severely lacking in ventilation, air change has become minimal and the atmosphere often contains far more CO2 and water vapour than is healthy for us (some suggest that inside air contains more than 10 times the pollution of outside air). The downside of this is that increased humidity provides an ideal breeding ground for unwanted (and commonly unseen) visitors such as moulds and mildews, and house dust mites (image above). In fact, a temperature range of ~21C to 24C and a relative humidity range of ~60% to 80%, a surprisingly common set of conditions in modern houses, provide almost perfect conditions for the common house dust mite to survive and proliferate giving rise to allergies and allergic reactions. The higher humidity also provides excellent conditions for moulds and mildews in rooms that are less often utilised, and perhaps not heated quite as much.
We are told that every house has resident dust mites to some degree, they live in our carpets, our bedding and any other soft furnishings, but they are tiny, almost microscopic things that can't do us any harm, can they? Well, unfortunately, although they may be almost microscopic, they are actually quite harmful to humans in some circumstances. Anyone who has asthma, or is prone to allergies, can have a major problem. Dust mite faeces, their skin casts, and bits of their dead skeletons contain substances that are thought to trigger asthma attacks, inflammation in the nose, and even eczema in sensitive people.
There is no proven direct correlation between the indoors air that we now breathe and the incidence of asthma, allergies etc. However, there are some interesting facts that seem to closely correspond with the 21st century mode of living.
* Almost a third of the U.K. population will develop an allergy at some time in their lives.
* Almost 1 in 8 children has asthma and 85% of these are allergic to house dust mites.
* More than 5 million people in the UK now have asthma.
* About 6 million people in the UK have eczema.
* Asthma, eczema and rhinitis have increased almost three-fold over the last 20 years.
* Allergies appear to increase at about 5% per year and almost half of those affected are children.
Abstracted from various publications by: National Asthma Campaign, Allergy UK and the R.C.P. [Royal College of Physicians].
No one knows exactly what has caused the asthma epidemic; there are multiple and conflicting theories but according to Professor Duncan Geddes of the National Asthma Campaign, "It's also something to do with the way we're living in modern housing - little ventilation, damp housing, more carpets and more dust make asthma more common."
A 2003 research report concluded that, "This trial, when taken in conjunction with the growing body of scientific literature, supports the view that ..... changes to the design and use patterns of our dwellings are highly likely to be the most significant single driver producing the current asthma pandemic in Britain. If the levels of allergenic protein found in the dust reservoirs sampled in this trial are typical ..... a significant proportion (80%) of the current asthma pandemic is due to HDM (House Dust Mite) allergen exposure."
See Ref 1 below.
There are other hypothesized causes for this 21st century epidemic like the materials we use in our homes, the chemicals we use to clean them and the materials we have used to construct them; all of which may give off potentially dangerous pollutants known as VOCs [Volatile Organic Compounds]. Yet, although commonly used in our housing, with improved ventilation they should not exist in sufficient quantities to do us any harm.
Perhaps improving the quality of the air and the amount of ventilation in our houses could therefore be seen as a major stepping stone towards minimizing asthma and allergies. We cannot be absolutely certain, but increasing the amount of fresh dry air blown through our hermetically sealed boxes has got to be beneficial to the way that we now live. We would certainly makes the conditions for dust mites and moulds significantly less tolerable, and blow out some of the potential VOCs.
Maybe our Grandparents were right all along, they understood the need for ventilation; 'You should always sleep with your window open, even when its freezing outside; and you should air your bedding at least once a week'.
SolarVenti can't put your bedding out to air for you, but it will dramatically improve the quality of the air in your property and reduce the dampness in your house making the environment intolerable for moulds and tough for unwanted parasites such as house dust mites.
Ref 1: SG Howieson, A Lawson et al: Building Services Engineering Research and Technology 24,3 (2003)
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